LAN and Telecom Cabling Program to Estimate Cat 5 Cable Length

> Dan P wrote:
>
>
>
>

> > Hello all,
> > I just have a quick question. Has someone written a program that
> > measures, say, the ping between a computer and a router and takes that
> > and estimates the length of a network cable? I was just wondering if
> > something like this was out there.

>

> > Thanks,
> > Dan P

>
> It just doesn't make sense: to accommodate for all possible combinations
> of lengths that a pair of Ethernet devices may encounter (from 0 to 100
> meters), the devices are designed to hold the data received in the buffer
> memory for at least the duration of the longest trip - 100 meters.
> Therefore, any measurement you might be able to take this way (without
> arguing whether it's even possible to measure such tiny time interval with
> devices not specifically designed for that) will always show one length -
> 100 meters (295 ft)
>
> --
> Dmitri Abaimov, RCDD
> http://www.cabling-design.com
> Cabling Forum, color codes, pinouts and other useful resources for
> premises cabling users and pros
> http://www.cabling-design.com/homecabling
> Residential Cabling Guide
> -------------------------------------
>
>
>
>
>
> ##-----------------------------------------------##
> Article posted with Cabling-Design.com Newsgroup Archive
> http://www.cabling-design.com/forums
> no-spam read and post WWW interface to your favorite newsgroup -
> comp.dcom.cabling - 4651 messages and counting!
> ##-----------------------------------------------##

> 100 meters = 328 ft.

> It just doesn't make sense: to accommodate for all possible combinations
> of lengths that a pair of Ethernet devices may encounter (from 0 to 100
> meters), the devices are designed to hold the data received in the buffer
> memory for at least the duration of the longest trip - 100 meters.
> Therefore, any measurement you might be able to take this way (without
> arguing whether it's even possible to measure such tiny time interval with
> devices not specifically designed for that) will always show one length -
> 100 meters (295 ft)

> Dmitri(Cabling-Design.com wrote:

>> It just doesn't make sense: to accommodate for all possible
>> combinations
>> of lengths that a pair of Ethernet devices may encounter (from 0
>> to 100
>> meters), the devices are designed to hold the data received in the
>> buffer
>> memory for at least the duration of the longest trip - 100 meters.
>> Therefore, any measurement you might be able to take this way
>> (without
>> arguing whether it's even possible to measure such tiny time
>> interval with
>> devices not specifically designed for that) will always show one
>> length -
>> 100 meters (295 ft)

> Actually, the longest trip may be far greater than 100 M. For example,
> on
> 10base5 network, the maximum distance is 500M and fibre can go much
> further
> than that. Also even with CAT5 on a switch, you can go 200M etc.
> Ethernet, being a level 2 protocol, will make sure the packet gets
> placed
> on the wire, without experiencing a collision. Once 512 bits have been
> transmitted, it's considered collision free and the ethernet portion of
> the
> stack has no more concerns about the data, such as if it made it to the
> destination intact. It then becomes the responibililty of a higher
> layer
> (either TCP or the application, if UDP) to ensure end to end integrity.

> UDP apps might not worry about that.

> The 100M CAT5 limitation is due entirely to signalling limits and has
> nothing to do with collision detection etc.

> Don't know if that was true or not, but it
> made sense to me when I read it.